Some applications may require a different illumination map for different kinds of materials.
Up to three illumination maps can be authored for each vignette. The illumination map for a render operation is selected with the illum=
and or gloss=
commands.
Default selection If neither illum=
nor gloss=
are specified, the renderer will use the first authored illumination map (typically map A, aka the ‘Flat’ illumination map).
Automatic selection with gloss=
If illum=
is not specified or is set to -1, the renderer compares the specified gloss=
value with the gloss values associated with each illumination map in the vignette, and choose the illumination map whose gloss value is closest to the specified gloss=
.
Explicit selection with illum=
If illum=
is specified and set to 0, 1, or 2, the renderer will use the corresponding illumination map; gloss=
is ignored for the purpose of selecting the illumination map.
If the vignette contains only one illumination map, the renderer will use that map and ignore the illum=
and gloss=
commands.